Electromagnetic relay

ABSTRACT

An electromagnetic relay in which center contact spring means normally engages outer contact spring means on one side and is moveable into engagement with contact spring means on the other side upon energization of an electromagnetic actuator forming a part of the relay. The contact spring means are in the form of leaf springs having contact elements at one end and being supported near the other end by a block of electrical insulating material having lateral slits into which the spring means are inserted. The slits are inclined relative to each other and thereby predetermine the preload on the individual spring means. The block has at least one wall portion projecting therefrom which has abutment elements interposed between the center spring means and the outer spring means to limit the movement of the latter toward the former. Advantageously, each contact spring means is in the form of a pair of laterally spaced springs between which the aforementioned wall is disposed.

United States Patent 1 Pfenning 1 July 31, 1973 ELECTROMAGNETIC RELAY[75] Inventor: Hans Pfenning, Lauffen, Germany [73] Assignee: Bach &Co., Heilbronn, Germany [22] Filed: Apr. 20, 1972 [2]] Appl. No.:245,739

[30] A Foreign Application Priority Data Apr. 22, 1971 Germany" P 21 1?734,2

[52] US. Cl. 335/135, 200/166 J [51] Int. Cl. 1101b 63/04 [58] Field ofSearch 335/135; 200/166 .1

[56] References Cited UNITED STATES PATENTS 3,256,401 6/1966 Dawson335/135 FOREIGN PATENTS OR APPLICATIONS 5/1962 7 Austria 335/135 PrimaryExaminer-Harold Broome Att0rneyWalter Becker [57] ABSTRACT Anelectromagnetic relay in which center contact spring means normallyengages outer contact spring means on one side and is moveable intoengagement with contact spring means on the other side upon energizationof an electromagnetic actuator forming a part .ofthe relay. The contactspring means are in the form of leaf springs having contact elements atone end and being supported near the other end by a block of electricalinsulating material havinglateral slits into which the spring means areinserted. The slits are inclined relative to each other and therebypredetermine the preload on the individual spring means. The block hasat least one wall portion projecting therefrom which has abutmentelements interposed between the center spring means and the outer springmeans to limit the movement of the latter toward the former.Advantageously, each contact spring means is in the form of a pair oflaterally spaced springs between which the aforementioned wall isdisposed.

5 Claims, 3 Drawlng Figures PATENIEU JUI. 3 1 I915- ELECTROMAGNETICRELAY The present invention relates to an electromagnetic relay with acontact spring set which comprisesat least three contact springs thatare approximately parallel to each other. The intermediate contactspring of the relay is on both sides provided with contact elements andrests under an elastic preload against the inn'er'contact spring whichis'adjacent to the armature of therelaylThe intermediatecontact springisby means'of the armature lifted in response to the armature beingattracted and is pressed against the outer counter contact. Finally, therelay is provided withan auxiliary holding device for connecting andinsulating the contact springs. With contact spring sets of heretoforeknown electromagnetic'relays, stamped out hard paper plates are providedfor insulating and connectingthecontact springs. These hard paper platesarealternately with the-contact springs stacked on'e upon the other, andthen by means of screws vertically cr'ossing'the layers or by meansot'rivets the hard pape'r platesarefirmly pressed against the'i'ron core ofthe relay orasupporting body. In addition thereto,- it is known forpurposesof obtaining the necessary contact pressure, as it is're'quiredin rest position of'the, relay, to provide wedge-shaped intermediatelayers between the contact springs which layers will assure the prelo'adfor the contact springs:

Witht'hese known'arr'ang'ements, the assembly and installation of theindividual elements pertaining to'the contact spring'set requireconsiderable time. Thistime requirement increases w'ith'the increase inth'enumber of the Contact springs pertaining toa" contact spring set.

elements which in the rest position of the relay under an elasticpreload rest'against the'inner c'ounter contact spring which is adjacentto the armatureof therelay and which is lifted off in response to theenergization of the relay and is pressed againstthe outer countercontact. In this instance not only the contact pressure generated atthe-inner counter contact will have to be assured in its rest position;but also a sufficient counter pressure must be obtained'if theintermediate contact spring in the working position 'of the relay ispressed against the outer. counter contact; A further difficultyfrequently consists in that during the mutual engagement anddisengagement of the contact elements arranged on the intermediatecontactspring and on one of the counter contact springs, a low slidingfrictidn is to be created which will eountei-acrthe formation'ofoitidicfilms or skins and makes it necessary that the counter contactsprings slightly yield under contact pressure exerted by theintermediate spring andca'n es pi r With a heretofore known arrangementof this type, pressed parts of insulating material are provided for acontact spring set. These pressed parts of insulating material arealternately stacked with the contact springs and inthis connectiongenerate the preload necessary for the contact forks between theindividual contact springs, the preload" resulting from clamping thecontact springs together; In order to: obtain the-desired alignment ofthe contact springs duringthe assembly, according to this knownarrangement corresponding to themost recent state of. the art, two partspressed of synthetic material which embrace a contact springtherebetween are provided with protruding: noses, while anotheroppositely located pressed part is provided with correspondingreces'ses;the noses. extending through two bores in the contact spring. Since,however, with this known arrangement it-is necessary to provide a numberof different pressed parts of insulating material in order to take intoconsideration the different spacing between the contact springs and togenerate thev tension forces necessary in theposition of'operation, theassembly can be effected only manually while great care has to be takenin this connection.

Moreover, not only a corresponding thorough work control is necessary,but the necessary formed or molded parts have to be kept in stock ingreat numbers for the manufacturing processand also-for a possiblereplacement. I i I 1v Itis; therefore, an object of the presentinvention so to design 1 the relay, which comprisesa contact spring 'setincluding at least three contact; springs, that the assembly will begreatly facilitated while the necessary contact pressure will be assuredin the rest position of the intermediate contact spring and also in the'working position of this c'ontac't spring. '1

This object and other objects and advantages of-the invention willappear moreclearly from the following specification in connection withvthe'accompanying drawing, in'whichz v v FIG. l shows a relay accordingtothepresent invention asseen from the side and at a scale whichcorrehasat least three slits or cuts respectivelyreceiving one contact springeach which are inclined relative to the base surface ofthe insulatingblock and the inclination of which determines the elastic preloadof thecontact springs. The insulating block furthermore is provided with atleast two supporting arms extending in" a direction transverse tothecontact springsrone of thesupporting arms forming an abutment for theouter counter contact spring, whereas the other supporting arm servesfor engagement with the inner contact spring."

In order to assure thatfor purposes of obtaininga slight contactfriction the two counter contact springs will be able under'the pressureof the intermediate contact spring slightly to yield, it issuggeste'daccording to a further development-of the invention to arrangethesupporting arms in the space between 'theinte'rmediate contact springandthe twocounter contact springs. Inas'much as the insulating block isexpediently made in the form of a pressed member ot synthetic material,the desired preload under which the counter contact springs, in view ofthe inclination of the slits or cuts receiving same, are directedagainst the supporting arms may be obtained without any post-adjustmentmerely by connecting the supporting arms to the insulating block bymaking them one piece therewith. With such a design of the insulatingblock it is particularly advantageous to mount the supporting arms on awall formed onto the insulating block which wall in the longitudinaldirection of the contact springs and at least approximately parallelthereto protrudes from the insulating block. Such wall will assure notonly the spacing of the supporting arms and their counter springs fromthe intermediate contact spring but will also protect the en- .tirecounter spring set against mechanical damage which may occur whenmounting the relay in a larger unit and may also occur during a laterchecking operation.

The invention may advantageously be employed with such electromagneticrelays in which the contact spring set is equipped with contact springsof which each two are arranged in a common plane adjacent to each other.f each two contact springs located in the same plane adjacent to eachother, one spring belongs to one of two contact sets whereas the otherspring belongs to another one of two contact sets. These contact setsmay preferably be designed as reversing contact sets. In such aninstance a particularly simple but stable symmetrical construction ofthe contact spring set may be realized by providing the insulating blockfor each of the contact springs with one of two cuts or slits which arelocated in the same plane and extend from two oppositely located blocksides to the vicinity of another cut or slit while maintaining anintermediate Web for holding the block together. If in the abovementioned manner as support for the supporting arms there is provided awall formed onto the insulating block, it is possible with a symmetricalconstruction to obtain a very advantageous and complete contactprotection when the formed-on wall between the two contact setsrespectively forming a group forms an extension of the intermediate webof the insulating block. For simple relay constructions it is desiredfor returning the relay armature to its disengaged position not to haveto provide special return springs. It is rather desired to takeadvantage of the returning force of the movable contact spring orcontact springs by providing between the movable contact spring orsprings and the armature a plunger stud which has one end restingagainst the contact spring or springs and has its other end restingagainst an extension which preferably protrudes at a right angle fromthe armature. In such an instance the wall formed onto the insulatingblock as support for the supporting arms affords the possibility toprovide in this wall a groove-shaped cutout for guiding the plungerstud.

Referring now to the drawing in detail, the illustrated miniature relayhas arranged on the pressed body of synthetic material a fine wire coil11, and an iron core 12 extending through the coil, which core protrudesat one coil end beyond the body 10 and at its other end is riveted to anangle member 13 forming a part of the iron core. The longer leg 14 ofthe angle member 13 has its end section designed to form a knife edgebearing 15 for a movable hinged armature 16 which is secured on the'edgeof leg 14 by means of a holding plate 17. The'contact spring set forminga compact construction group is connected to the leg 14 by a holdingscrew 18 extending all the way through. This contact spring set 20 issymmetrically arranged with regard to a plane located in the axis of thecoil 11 and of the iron core 12 as indicated in FIG. 2 by the line A A.One of two contact sets B and C is arranged on one side of the plane ofsymmetry while the other one of these contact sets is arranged on theother side of the plane of symmetry. Each of the contact sets B and Ccomprises an intermediate contact spring 22 coupled to the armature 16by the plunger stud 21, and two counter contact springs, namely theinner contact spring 24 and the outer contact spring 25. FIG. 1 showsonly that one of these contact springs which pertains to the contact setB. The contact set C is built up in a corresponding manner.

, In order to permit an easy assembly of the contact springs and toassure a high stability of the contact spring sets, there is provided aone-piece block 26 of insulating material having formed thereonto asupporting wall 27 located in the plane of symmetry A A. This supportingwall 27 extends perpendicularly to the leg 14 of the angle member 13 ofiron and protects the two contact sets B and C against mechanical damagewhile protecting the contact sets B and C electrically against sparkingor the like. For purposes of receiving the contact springs, theinsulating block 26 has in a common plane two cuts or slits each whichextend from two block sides 28 and 29 located opposite to each other tothe vicinity of the respective other slit or cut while leaving anintermediate web to assure the coherence of the block. The supportingwall 27 is located along the extension of this web. These cuts are shownin FIG. 3 for the contact set B and are designated with the referencenumerals 31, 32 and 33, and are also shown for the contact set C and aredesignated with the reference numerals 34, 35 and 36. The slit 31intended for receiving the outer contact spring 25 is inclined withregard to the base surface 40 of the insulating block 26 which basesurface is provided with two plug studs 37 and 38 in such a way that thecontact spring 25, when being inserted into the slit, will automaticallyobtain the necessary preload which, when energizing the relay, willassure a proper contact with regard to the intermediate contact spring22 which is then moved by the hinged armature 16 through the plungerstud 21.

For purposes of precisely fixing the outer contact spring 25, there isaccording to the present invention provided a supporting arm 41 for thecontact spring 25. The contact spring 25 rests on the supporting arm 41at the preload resulting from the inclination of the slit 31 whereby thecontact spring 25 is fixed in its proper position for making a contact.In an analogous manner,

the slit 33 intended for receiving the lower and inner counter contactspring 24 ascends upwardly and is associated with a second supportingarm 42. The inner counter contact spring 24 rests from below under apreload against the second supporting arm 42 when the intermediatecontact spring 22 starts to lift itself off with its lower contactelement 43. The supporting arm 42 then will determine the preciselocation of the intermediate contact spring 22 at which the connectionto the contact member 44 will be disengaged. In a corresponding manner,the inclination of the slit 32 intended for the intermediate contactspring 22 is directed slightly upwardly and will then generate thecontact pressure between the contact members 43 and -44 which is alsonecessary in the rest position of the relay.

Numerals 45 designate the contact elements on contactsprings 25.

in conformity with the symmetric construction of the contact spring set,also for the two counter contact springs of the contact set C (FIG. 2showing only the outer contact springs 25) there are provided twosupporting arms 46 and 47. These supporting arms 46 and 47 will similarto the supporting arms 41 and 42 make it possible that during the makingof contact their pertaining contact springs can slightly yield under thecontrol pressure so that at the contact surfaces there will be obtaineda slight sliding friction which will assure a permanent satisfactorymaking of contact. Simulta neously, the supporting arms will fix theengaging and disengaging position. In this way, in spite of the smalldimensions of the miniature relay, a safe determination for the controlbehavior of the relay will be obtained.

The supporting wall 27 is for purposes of guiding the plunger stud 21provided with a groove-shaped cutout 50. The plunger stud 21 can bemoved upwardly in the cutout 50, when the relay is energized to such anextent that its lateral extensions 51 can press the intermediate contactsprings 22 against the outer counter contact springs 25.

lt is, of course, to be understood that the present invention is, by nomeans, limited to the particular showing in the drawing but alsocomprises any modifications within the scope of the appended claims.

What is claimed is:

1. In an electromagnetic relay, a contact spring assembly comprising:ribbon-like center contact spring means and outer contact spring meansarranged in generally parallel superposed spaced relation, holding andinsulating means supportingly engaging said spring means in a regionnear one end and interengageable contact element means on said springmeans near the other end, an'electromagnetic actuator having a frameconnected to said holding and insulating means adjacent one of saidouter contact spring means, said center contact spring means normallyholding the contact element means thereon in engagement with the contactelement means on said one'outer contact spring means,

said electromagnetic actuator having an armature operatively connectedto said center contact spring means and operable when energized to movesaid center contact spring means to cause the contact element thereon toseparate from the contact means on said one outer spring means and toengage the said contact means on the other outer spring means, saidholdingand insulating means having separate slits receiving said regionsof said contact spring means, said slits being inclined to each other topredetermine the elastic preload on said contact spring means, andabutment elements engageable with said outer contact spring means tolimit the movement of said outer contact spring means toward said centerspring means, said abutment elements protruding into the spacebetweensaid center contact spring means and respective ones of saidouter contact means, and being formed in one piece with said holding g 6and insulating means.

2. Anelectromagnetic relay according to claim 1 in which said holdingand insulating means comprises at least onewall portion substantiallyparallel to said contact spring means, said abutment elements beingintegral with said wall portion and protruding therefrom into the spacebetween said center contact spring means and. respective ones of saidouter contact spring means.

3. An electromagnetic relay according to claim 1 in which each of saidcenter andouter spring means comprise a pair of springs in laterallyspaced relation, said holding and insulating means having a said slitfor each spring extending inwardly from the respective side of saidholding and insulating means, the central portion of said holding andinsulating means between the respective slits for each pair of springsbeing uninterrupted. v

4. An electromagnetic relay according to claim 1 in which each of saidcenter and outer spring means comprise a pair of springs in laterallyspaced relation, said holding and insulating means having a said slitfor each spring extending inwardly from the respective side of saidholding and insulating means, the central portion of said holding andinsulating means between the respective slits for each pair of springsbeing uninterrupted, a wall portion integral with said central portionof said holding and insulating means and extending outwardly therefromin the space between the respective springs of each pair of contactspring means, said abutment elements being integral with said wallportion and protruding in the lateral direction therefrom into thespaces between the respective springs of said pair of center contactspring means and the respective springs of said pairs of outer contactspring means.

5. An electromagnetic relay according to claim 1 in which .each of saidcenter and outer spring means comprise a pair of springs in laterallyspaced relation, said holding and insulating means having a said slitfor each spring extending inwardly from the respective side of saidholding and insulating means, the central portion of said holding andinsulating means between the respective slits for each pair of springsbeing uninterrupted, a wall portion integral with said central portionof said holding and insulating means and extending outwardly therefromin the space between'the respective springs of each pair of contactspring means, said abutment elements being integral with said wallportion and protruding in the lateral direction therefrom into thespaces between the respective springs of said pair of center contactspring means and the respective springs of said pairs of outer contactspring means, said wall portion comprising a cutout facing saidelectromagnetic actuator, and plunger means reciprocably guided in saidcuto'ut and disposed between said center contact spring means and thearmature of said electromagnetic actuator and forming the operativeconnection of said armature to said center contact springs.

t i t t

1. In an electromagnetic relay, a contact spring assembly comprising:ribbon-like center contact spring means and outer contact spring meansarranged in generally parallel superposed spaced relation, holding andinsulating means supportingly engaging said spring means in a regionnear one end and interengageable contact element means on said springmeans near the other end, an electromagnetic actuator having a frameconnected to said holding and insulating means adjacent one of saidouter contact spring means, said center contact spring means normallyholding the contact element means thereon in engagement with the contactelement means on said one outer contact spring means, saidelectromagnetic actuator having an armature operatively connected tosaid center contact spring means and operable when energized to movesaid center contact spring means to cause the contact element thereon toseparate from the contact means on said one outer spring means and toengage the said contact means on the other outer spring means, saidholding and insulating means having separate slits receiving saidregions of said contact spring means, said slits being inclined to eachother to predetermine the elastic preload on said contact spring means,and abutment elements engageable with said outer contact spring means tolimit the movement of said outer contact spring means toward said centerspring means, said abutment elements protruding into the space betweensaid center contact spring means and respective ones of said outercontact means, and being formed in one piece with said holding andinsulating means.
 2. An electromagnetic relay according to claim 1 inwhich said holding and insulating means comprises at least one wallportion substantially parallel to said contact spring means, saidabutment elements being integral with said wall portion and protrudingtherefrom into the space between said center contact spring means andrespective ones of said outer contact spring means.
 3. Anelectromagnetic relay according to claim 1 in which each of said centerand outer spring means comprise a pair of springs in laterally spacedrelation, said holding and insulating means having a said slit for eachspring extending inwardly from the respective side of said holding andinsulating means, the central portion of said holding and insulatingmeans between the respective slits for each pair of springs beinguninterrupted.
 4. An electromagnetic relay according to claim 1 in whicheach of said center and outer spring means comprise a pair of springs inlaterally spaced relation, said holding and insulating means having asaid slit for each spring extending inwardly from the respective side ofsaid holding and insulating means, the central portion of said holdingand insulating means between the respective slits for each pair ofsprings being uninterrupted, a wall portion integral with said centralportion of said holding and insulating means and extending outwardlytherefrom in the space between the respective springs of each pair ofcontact spring means, said abutment elements being integral with saidwall portion aNd protruding in the lateral direction therefrom into thespaces between the respective springs of said pair of center contactspring means and the respective springs of said pairs of outer contactspring means.
 5. An electromagnetic relay according to claim 1 in whicheach of said center and outer spring means comprise a pair of springs inlaterally spaced relation, said holding and insulating means having asaid slit for each spring extending inwardly from the respective side ofsaid holding and insulating means, the central portion of said holdingand insulating means between the respective slits for each pair ofsprings being uninterrupted, a wall portion integral with said centralportion of said holding and insulating means and extending outwardlytherefrom in the space between the respective springs of each pair ofcontact spring means, said abutment elements being integral with saidwall portion and protruding in the lateral direction therefrom into thespaces between the respective springs of said pair of center contactspring means and the respective springs of said pairs of outer contactspring means, said wall portion comprising a cutout facing saidelectromagnetic actuator, and plunger means reciprocably guided in saidcutout and disposed between said center contact spring means and thearmature of said electromagnetic actuator and forming the operativeconnection of said armature to said center contact springs.